Nonvolatile memory device and cross point array device including the same

Abstract

Provided is a nonvolatile memory device including a lower electrode on a substrate, an upper electrode on the lower electrode, a tunnel barrier pattern between the lower electrode and the upper electrode, and a fixed charge pattern in contact with the lower electrode and spaced apart from the tunnel barrier pattern with the lower electrode therebetween. The tunnel barrier pattern includes an anti-ferroelectric material. The lower electrode includes a first material. The upper electrode includes a second material. The first material and the second material have different work functions.

What is claimed is: 
     
       1. A nonvolatile memory device comprising:
 a lower electrode on a substrate; 
 an upper electrode on the lower electrode; 
 a tunnel barrier pattern between the lower electrode and the upper electrode; and 
 a fixed charge pattern in contact with the lower electrode and spaced apart from the tunnel barrier pattern with the lower electrode therebetween, 
 wherein the tunnel barrier pattern includes an anti-ferroelectric material, 
 the lower electrode includes a first material, 
 the upper electrode includes a second material, and 
 the first material and the second material have different work functions. 
 
     
     
       2. The nonvolatile memory device of  claim 1 , wherein a difference in work function between the first material and the second material is greater than 0.5 eV. 
     
     
       3. The nonvolatile memory device of  claim 1 , wherein the fixed charge pattern contains any one among SiO 2 , HfO 2 , ZrO 2 , TiO 2 , VO, Nb 2 O 5 , Ta 2 O 5 , Al 2 O 3 , Y 2 O 3 , and Ln 2 O 3 . 
     
     
       4. The nonvolatile memory device of  claim 1 , wherein:
 the first material has a greater work function than the second material; and 
 the fixed charge pattern has a negative charge. 
 
     
     
       5. The nonvolatile memory device of  claim 1 , wherein:
 the first material has a less work function than the second material; and 
 the fixed charge pattern has a positive charge. 
 
     
     
       6. The nonvolatile memory device of  claim 1 , wherein the first material and the second material comprise any one among a metal, a metal oxide, and a semiconductor material,
 the metal containing any one among TiN, TaN, NbN, VN, ZrN, HfN, TiAlN, W, Cu, Pt, Mo, Ni, and Al, 
 the metal oxide containing any one among RuO 2 , IrO 2 , ITO (Indium Tin Oxide), IGZO (Indium Gallium Zinc Oxide), IZO (Indium Zinc Oxide), AZO (Aluminum-doped Zinc Oxide), and HIZO (Hafnium Indium Zinc Oxide), and 
 the semiconductor material containing any one among n-type Si, p-type Si, Ge, and SiGe. 
 
     
     
       7. The nonvolatile memory device of  claim 1 , wherein the anti-ferroelectric material contains Hf x Zr 1-x O 2  (x>0) or ZrO 2 . 
     
     
       8. The nonvolatile memory device of  claim 1 , wherein:
 the anti-ferroelectric material contains Hf x Zr 1-x O 2  (x>0); and 
 in the tunnel barrier pattern, Zr is contained in a greater amount than Hf. 
 
     
     
       9. The nonvolatile memory device of  claim 1 , wherein the tunnel barrier pattern has a thickness of about 1 nm to about 10 nm. 
     
     
       10. The nonvolatile memory device of  claim 1 , wherein the fixed charge pattern has a thickness of about 4.2 nm to about 8 nm. 
     
     
       11. A nonvolatile memory device comprising:
 an anti-ferroelectric tunnel junction pattern on a substrate; and 
 an oxide layer between the substrate and the anti-ferroelectric tunnel junction pattern, 
 wherein the anti-ferroelectric tunnel junction pattern includes: 
 a lower electrode; 
 an upper electrode on the lower electrode; and 
 a tunnel barrier pattern between the lower electrode and the upper electrode, 
 the oxide layer is spaced apart from the tunnel barrier pattern with the lower electrode therebetween, and is in contact with the lower electrode, 
 the tunnel barrier pattern includes an anti-ferroelectric material, 
 the anti-ferroelectric material contains Hf x Zr 1-x O 2  (x>0), 
 in the tunnel barrier pattern, Zr is contained in a greater amount than Hf, and 
 the oxide layer contains a fixed charge. 
 
     
     
       12. The nonvolatile memory device of  claim 11 , wherein the upper electrode and the lower electrode comprise materials having different work functions. 
     
     
       13. The nonvolatile memory device of  claim 11 , wherein:
 the lower electrode contains RuO 2 ; 
 the upper electrode contains TiN; and 
 the oxide layer contains HfO 2 . 
 
     
     
       14. The nonvolatile memory device of  claim 11 , wherein the oxide layer has a greater oxygen vacancy concentration than the tunnel barrier pattern. 
     
     
       15. The nonvolatile memory device of  claim 11 , further comprising a transistor provided on the substrate,
 wherein one terminal of the transistor is electrically connected to the anti-ferroelectric tunnel junction pattern. 
 
     
     
       16. A cross point array device comprising:
 a first conductive line extending along a first direction; 
 a second conductive line extending along a second direction crossing the first conductive line; and 
 a pillar structure provided between the first conductive line and the second conductive line, 
 wherein the pillar structure includes a fixed charge pattern, a lower electrode, an anti-ferroelectric pattern, and an upper electrode, which are stacked in order, 
 the fixed charge pattern is in contact with the lower electrode, and is spaced apart from the anti-ferroelectric pattern with the lower electrode therebetween, 
 the lower electrode includes a first material, 
 the upper electrode includes a second material, and 
 the first material and the second material have different work functions. 
 
     
     
       17. The cross point array device of  claim 16 , wherein:
 the first material has a greater work function than the second material; and 
 the fixed charge pattern has a negative charge. 
 
     
     
       18. The cross point array device of  claim 16 , wherein:
 the first material has a less work function than the second material; and 
 the fixed charge pattern has a positive charge.